Method for increasing the spinning rate of cellulose organic acid ester filaments



United States Patent 3,272,638 METHOD FOR INCREASING THE SPINNING RATE UF ClELLULOSE ORGANIC ACID ESTER FILA- MENTS George Patrick Touey and John Edward Kiefer, Kingsport, Tenn., assignors to Eastman Kodak Company, Rochester, N.Y., a corporation of New Jersey No Drawing. Filed Feb. 4, 1964, Ser. No. 342,544 7 Claims. (Cl. 106-176) This application is a continuation-in-part of Touey and Kiefer US. application Serial No. 156,464, filed December l, 1961, and now abandoned, in which claims have been allowed.

This invention relates to ester additives for fibrous material and the employment thereof in spinning solutions. More particularly, it relates to filaments, yarns, tows and filters containing certain sugar esters 'and preparation of same.

It is sometimes desirable to add a bonding agent to man-made fibrous tow such as cellulose ester tow, especially when such tow is intended for use in non-woven products, including tobacco smoke filters. Bonding may be accomplished by the application of nontacky free-flowing organic plasticizer. Touey et al. U.S. Patents 3,003,- 504 and 3,008,474 disclose plasticizer bonding agents particularly adapted for use on crimped cellulose acetate filter tow. I

Some of these plasticizers, although highly satisfactory for bonding, sometimes do not develop the desired bonding effect until a period of storage. For example, it requires about two hours storage at room temperature for a freshly prepared cellulose acetate filter rod containing certain plasticizers to develop the desired rigidity for cutting into smaller segments for attachment to cigarettes. This curing time or period may permit some form distortion in the shaped articles prepared from the plasticizer-treated tow. Therefore, provision of tow or filter containing a bonding agent with a quick curing or rigidity-producing time represents a highly desirable result. After extending investigation we have developed a well and speedily bonded fibrous product as well as one which has the further advantage of being produced by addition of certain ester additives to spinning solution such that filaments may be extruded at an increased spinning rate with an accompanying decrease in amount of solvent used.

One object of this invention is to provide filaments, yarn, tow and products made therefrom, such .as tobacco smoke filter elements, containing an efiicient bonding agent. Another object is to provide a method of increasing the rate of extrusion of filaments from a spinning composition. A further object is to provide a process for producing tobacco smoke filter elements and other non-woven fibrous products the fibers of which are bonded by an ester which imparts early rigidity thereto. Further objects will be apparent hereinafter.

In accordance with the present invention, these objects are accomplished by adding to an organic solvent spinning solution containing a major portion of a cellulose organic acid ester such as cellulose acetate a minor proportion, viz., enough to provide a fiber content of to 35 percent by weight, preferably 10 to 30 percent by weight, of a low molecular weight noncrystallizing aliphatic acid ester of a sugar selected from the following completely esterified mixed esters of glucose or sucrose:

glucose acetate propionate glucose acetate isobutyrate glucose propionate isobutyrate sucrose acetate propionate sucrose acetate isobutyrate sucrose propionate isobutyrate ice The proportion of solids in the spinning solution is in this way increased, thereby enabling considerable saving quantity-wise as to spinning solution. Thus, more filaments may be spun from less spinning composition. The mixed sucrose acid esters may be added to the spinning composition just prior to the spinning operation. It is preferred that these additives be thoroughly mixed in the spinning composition just prior to spinning.

The spinning composition thus is characterized by a high solids content and a decreased volatile solids content, and this supplies the requirement for permitting spinning at higher speeds than the conventional lower solid content cellulose acetate spinning solutions with subsequent employment in the formation of a bonded nonwoven Web product of excellent quick rigidity.

The .spinning composition containing the cellulose acetate, the mixed sucrose ester and the liquid vehicle is extruded through spinnerette orifices into a spinning cabinet where the liquid is removed by volatilization and the resulting filaments continuously removed from the cabinet by rolls or other conventional means.

Previously, when any appreciable amount of a monomeric material was added to cellulose acct-ate spinning solutions, the strength, elongation and/or flow point of the filaments produced were subject to some impairment. This was the situation to some extent, for example, when the abovementioned Touey et al, plasticizers for cellulose acetate were incorporated into the cellulose acetate spinning solutions prior to spinning. It has now been found that relatively large amounts of the lower molecular weight, mixed, noncrystallizing aliphatic acid sugar esters of Touey and Kiefer US. Patent 2,931,802 may be added to cellulose acetate spinning compositions without substantial risk of impairing the above-named properties. In fact, the versatility of the yarn produced in accordance with the present invention is increased in that moisture regain, dyeing characteristics, density and solvent susceptibility of the yarn may be varied by varying the amounts of these particular sugar ester additives.

As indicated above, the sugar esters must be soluble in the volt-aile liquid employed in preparing the spinning composition. Also, they should be compatible with the cellulose ester of the spinning composition and not increase the viscosity of the spinning solution greatly. We have found these sugar esters do not exude to the surface of the cellulose acetate filaments nor do they lower the softening points of the filaments to any appreciable degree. This contrasts to the use of plasticizers in the spinning solution which in general may lower the softening point of the filaments. As mentioned above, the sugar esters hereindescribed are non-crystallizing, completely esterified or highly esterified mixed fatty acids of sucrose or glucose containing a combination of acetyl and isobutyryl groups or propionyl or isobutyryl groups as 'acetyl constituents. Sucrose acetate isobutyrate and sucrose propionate isobutyrate are particularly effective according to this invention. These compounds are an entirely new type of sucrose ester and are disclosed in abovementioned Touey et al. U.S. Patent 2,931,802 of April 5, 1960. They differ markedly from the unmixed lower aliphatic acid esters of sucrose such as sucrose octaacetate or sucrose octapropionate in that they do not crystallize. They differ from the non-crystallizing unmixed sucrose esters such as sucrose octabutyrate, sucrose octavalerate and sucrose octahexanoate in that they are extremely viscous semi-solids rather than oily liquids.

The amount of extender (ester additive) employed in the cellulose acetate spinning composition depends on the desired increase in the solids content of the composition and of course the required end properties of the yarn made therefrom. However, an amount of 10-40 percent of the sugar ester based on the weight of the cellulose organic acid ester has been found to be useful and an effective concentration range. Acetone is the preferred solvent (liquid vehicle) to use for making up spinning solutions in accordance with this invention, but either solvents common to both the cellulose ester and sucrose ester may be employed, as will be evident hereinafter.

The invention is further described in the following examples.

EXAMPLE 1 A solution consisting of 300 pounds of cellulose acetate (40 percent acetyl) and 900 pounds of acetone was divided into 6 equal parts. Varying amounts of a sucrose acetate isobutyrate, containing an average of 2 acetyl groups and 6 isobutyryl groups per sucrose molecule, were added to five of these solution examples, then all six samples were spun using a conventional spinning cabinet. In all cases, the denier of the yarn was held constant at 16 denier/ filament, 4,000 total denier and the spinning rate was adjusted so that 300 grams/min. of acetone were removed from the spun yarn by evaporation. Table I illustrates the increase in spinning rates obtained by the addition of the extender. The properties of the spun yarn are also listed in Table I.

sucrose propionate isobutyrate contained an average of 3 propionyl groups and 5 isobutyryl groups per sucrose molecule.

The spinning solution was dry spun into fibers using a conventional spinning cabinet. The denier of the yarn was held constant at 16 denier/ filament, 4,000 total denier and the spinning rate was adjusted so that 300 grams/min. of acetone was removed from the spun yarn by evaporation. The fibers were taken up at a rate of 246 meters/min. The maximum spinning speed obtainable from a similar dope which did not contain an additive (Example 1) was 224 meters/min. The fibers had a tensile strength of 1.27, 22 percent elongation, and a flow point of 230 C.

EXAMPLE 4 This example illustrates how the presence of our mixed sugar esters as represented by sucrose acetate isobutyrate within cellulose secondary acetate (40 percent acetyl) fibers facilitates the hardening of a filter rod from a crimped continuous tow of these fibers, especially when the tow is treated with glycerol triacetate.

A spinning dope, consisting of 80 pounds of cellulose acetate (40 percent acetyl), 20 pounds of sucrose acetate isobutyrate, and 300 pounds of acetone, was spun into Table l Yarn Properties Pounds of Sucrose Acetate Isobutyr- Uaxirnum ate Added to 200 lbs. of Spinning Spinning Strength, Percent Flow Point Percent Solution Speed Grams/ Elonga- (0.05 Grams/ Moisture Re- (Meters/Min.) Denier tion Denier) gain (72 F.,

/ EXAMPLE 2 A spinning solution of approximately 100 lbs. of cellulose triacetate, 270 pounds of methylene chloride and 30 pounds of methanol was divided into 2 equal parts. To one sample of the solution 15 pounds of sucrose tetraacetate tetraisobutyrate was added. Both solutions were spun on a conventional dry spinning ca'binet into a yarn of 5 denier/filament and 2500 total denier. The spinning rate was adjusted so that 300 grams of solvent per minute was removed from the cabinet. The addition of the sucrose acetate isobutyrate increased the yarn take-up rate from 360 meters/min. to 468 meters/ min.

Strength, Elonga- Flow Yarn Properties grams/denier tion, Point,

percent Without sucrose Acetate isobutyr- 1. 21 15 250 ate. With sucrose acetate isobutyrate 1. 23 14 248 A spinning solution'of approximately 100 pounds of cellulose acetate (40 percent acetyl), 300 pounds of acetone, 5 pounds of sucrose acetate isobutyrate, and 5 pounds of sucrose propionate isobutyrate was prepared. The sucrose acetate isobutyrate contained an average of 3 acetyl groups and 5 isobutyryl groups per sucrose molecule. The

filaments of 5 denier per filament. The completely esterified sucrose acetate isobutyrate had an acetyl content of 18.6 percent and an isobutyryl content of 39.4 percent and was prepared in the manner described in the Touey and Davis US. Patent 2,931,802.

The filaments, which had a strength of 1.25 g./denier and an elongation of 30 percent, were plied together into the form of a tow of 16,000 filaments. The tow was then crimped (16 crimps/inch) and processed into filter rods according to the methods described in the Crawford and Stevens patents. This consisted of running the tow through a filter rod assembly machine which bloomed it to a width of 12 inches, sprayed it with glycerol triacetate (8 percent added), recompacted it, and wrapped it with paper to form a cylindrical -mm. rod with a circumference equal to that of a standard cigarette.

These filter rods were soft to the touch when first prepared. However, after 15 minutes they had cured or hardened to an extent that they were then easily cut on a filter cigarette making machine to the usual 17-min. filter tip lengths. To test rod hardness within a few minutes after fabrication, one of the rods (5 minutes after preparation) was placed under a l-lb. load for 2 hours. This treatment did not produce an oval-shaped rod, which indicated the rod was sufficiently cured in 5 minutes to resist distortion by a small amount of pressure.

Cellulose acetate (40 percent acetyl) fibers without the sugar ester and having a strength of 1.30 g./den1er and an elongation of 31 percent were also prepared. These fibers (5 denier/filament) were plied together into the form of a tow of 16,000 filaments. The tow was then crimped 16 crimps/inch) and processed into filter rods containing 8 percent glycerol triacetate in the manner described above. These filter rods were still soft to the touch after 45 minutes and could not be rapidly processed into 17-mm. filters until about 90 minutes after y Were prepared. After one of the rods had aged for 5 minutes it was subjected to the l-lb. weight test for 2 hours. It had hardened to a permanent oval shape. Thus a 5-minute cure in this instance was insufficient to develop enough rigidity to resist distortion from the weight of other rods stacked thereon during normal production.

EXAMPLE 5 Five denier/filament yarns containing 18 percent of the following sugar esters were spun from an acetone solution containing cellulose acetate (39.8 percent acetyl) and one of the sugar esters.

A. Sucrose propionate isobutyrate-19.7 percent propionyl and 42.1 percent isobutyryl.

B. Sucrose acetate propionate17.2 precent acetyl and 38.1 percent propionyl.

C. Glucose acetate isobutyrate18.1 percent acetyl and 45.0 percent isobutyryl.

D. Glucose acetate propionate-16.8 percent acetyl and 43.2 percent propionyl.

E. Glucose propionate isobutyrate-22.8 percent propionyl and 42.6 percent isobutyryl.

All of the yarns had physical properties similar to those of commercial cellulose acetate yarn. These yarns were then converted into crimped, continuous tows of 16,000 filaments and 16 crimps/inch. They were finally processed into filter rods containing 8 percent glycerol triacetate in the manner described in Example 4.

Within 20 minutes after they were prepared all of the rods had developed enough rigidity to be processed into 17-min. filter tips and attached to cigarettes. Five minutes after they were prepared the rods were capable of withstanding a l-lb. weight without being distorted.

EXAMPLE 6 This example illustrates how the presence of our sugar esters in cellulose triacetate yarn (43.8 percent acetyl) converts the yarn to a glycerol triacetate bondable material for filters.

A spinning dope consisting of 100 pounds cellulose triacetate (43.8 percent acetyl), 270 pounds of methylene chloride, and 30 pounds of methanol was divided into 2 equal parts. To one sample of the dope 15 pounds of sucrose tetraacetatetetraisobutyrate was added. Both dopes were spun on a conventional dry spinning cabinet into yarn of 5 denier/filament. The yarn with the sugar derivative had a strength of 1.21 g./denier while the control yarn had a strength of 1.23 g./denier. Both yarns had an elongation of 20 percent.

Each yarn was converted to a crimped tow containing 16,000 filaments and the tow was subsequently crimped to contain 16 crimps/inch. Each of these tows was then processed into 90-min. filter rods, containing 8 percent triacetin, in the manner described in Example 4. Within 20 m-inutes after the rods containing the sugar ester were fabricated they had become rigid and could be cut into smaller lengths and attached to cigarettes. The control filter rods, however, were still soft after 24 hours storage indicating that the plasticizer had less or delayed action on the fibers.

From the preceding description and examples it is thought apparent that by addition of 5-35 percent of a low molecular weight non-crystallizing mixed aliphatic acid glucose or sucrose ester to a high acetyl content cellulose ester tow, particularly by mixing with the spinning solution, we have enabled production of filter elements of enhanced early rigidity.

Although the invention has been described in considerable detail with particular reference to certain preferred embodiments thereof, variations and modifications can be effected within the spirit and scope of the invention as described hereinabove, and as defined in the appended claims.

We claim:

1. In the method of dry spinning cellulose organic acid ester filaments, the step of increasing the spinning rate which consists in adding to the spinning solution prior to spinning, 10-40 percent based on the weight of the cellulose organic acid ester of a compound selected from the class consisting of non-crystallizing sucrose acetate isobutyrate, sucrose propionate isobutyrate and their mixtures.

2. In the method of dry spinning cellulose acetate filaments, the step of increasing the spinning rate which consists in adding to the spinning solution, prior to spinning, 10-40 percent based on the weight of the cellulose acetate of a compound selected from the class consisting of noncrystallizing sucrose acetate isobutyrate, sucrose propionate isobutyrate and their mixtures.

3. In the method of dry spinning cellulose triacetate filaments, the step of increasing the spinning rate, which consists in adding to the spinning solution prior to spinning, 10-40 percent based on the weight of the cellulose triacetate of a compound selected from the class consisting of non-crystallizing sucrose acetate isobutyrate, sucrose propionate isobutyrate and their mixtures.

4. A dry spinning solution consisting of approximately 50 pounds of cellulose acetate having a 40 percent acetyl content and 2.5-15 pounds of sucrose acetate isobutyrate having 2-acetyl and 6-isobutyryl groups per sucrose molecule dissolved in approximately 150 pounds of acetone.

5. A spinning solution consisting of approximately pounds of cellulose triacetate, 270 pounds of methylene chloride, 30 pounds of methanol and 15 pounds of noncrystallizing sucrose acetate isobutyrate.

6. A spinning composition comprising about 25 to 50 percent by weight of said composition of a cellulose ester selected from the group consisting of a modified cellulose secondary acetate of an acetyl content of 39-41 percent and modified cellulose triacetate of an acetyl content of 43-445 percent and about 10 to 40 percent by weight of a cellulose ester of a low molecular weight non-crystallizing mixed aliphatic acid sugar ester selected from the group consisting of glucose acetate propionate, glucose acetate isobutyrate, glucose propionate isobutyrate, sucrose acetate propionate, sucrose acetate isobutyrate and sucrose propionate isobutyrate.

7. The method of increasing the rate of spinning a composition comprising a cellulose ester contained in a liquid vehicle for said cellulose ester which comprises adding to the composition prior to spinning 10-40 percent based on the weight of the cellulose ester of a low molecular weight non-crystallizing mixed highly esterified aliphatic fatty acid sugar ester selected from the group consisting of glucose acetate propionate, glucose acetate isobutyrate, glucose propionate isobutyrate, sucrose acetate propionate, sucrose acetate isobutyrate and sucrose propionate isobutyrate.

References Cited by the Examiner UNITED STATES PATENTS 2,917,398 12/1959 Coover et a1 106169 2,931,802 4/1960 Touey et al. 106162 X 3,001,883 9/1961 Vivian et a1. 106162. 3,008,472 11/1961 Touey 131-208 3,019,119 1/1962 Hofiman et a1. 106169 3,025,861 3/1962 Cobb 131-208 3,057,743 10/ 1962 Touey et a1. 106169 ALEXANDER H. BRODMERKEL, Primary Examiner. D. J. ARNOLD, Assistant Examiner. 

1. IN THE METHOD OF DRY SPINNING CELLULOSE ORGANIC ACID ESTER FILAMENTS, THE STEP OF INCREASING THE SPINNING RATE WHICH CONSISTS IN ADDING TO THE SPINNING SOLUTION PRIOR TO SPINNING, 10-40 PERCENT BASED ON THE WEIGHT OF THE CELLULOSE ORGANIC ACID ESTER OF A COMPOUND SELECTED FROM THE CLASS CONSISTING OF NON-CRYSTALLIZING SUCROSE ACETATE ISOBUTYRATE, SUCROSE PROPIONATE ISOBUTYRATE AND THEIR MIXTURES. 